A wide variety of foams are commonly produced on a commercial scale and marketed. Foams of vulcanized rubbers and soft olefin plastics can be mentioned as typical examples of such foams.
However, the conventional vulcanized rubbers, although having excellent flexibility and elasticity, inevitably require a time-consuming crosslinking or vulcanization step for realizing these properties, which incurs high cost. On the other hand, it is known to use soft olefin plastics, for example, thermoplastic resins such as ethylene/vinyl acetate copolymer (EVA) and low-density polyethylene in the formation of foams. These soft olefin plastics are basically inferior in heat resistance to the vulcanized rubbers. Thus, they encounter problems such that the applicability of obtained foams is extremely limited and that defoaming is likely to occur because of poor tension at melting to thereby render the expansion ratio low, which defoaming results in apparent surface roughening. Further, in the use of EVA, an increase of vinyl acetate content enhances the tear strength and adherence thereof but deteriorates the abrasion resistance, surface hardness and cell denseness. Therefore, the balance of properties is difficult with the use of EVA. Still further, the specific gravity of EVA itself is high, so that there occurs a problem such that foams of desirably low specific gravity cannot necessarily be obtained.
Therefore, there is a demand for the development of a crosslinked olefin elastomer foam which has a high expansion ratio, is free from surface roughening attributed to defoaming, realizes a soft touch, exhibits a low compression set and is excellent in tear strength property and heat resistance, and the development of an elastomer composition for such a crosslinked foam.